I have read that Moly and Plasma-Moly top compression rings need a final hone that is fine; around 600 grit. However Hastings recommends 280 grit (talked to tech support). Also from their documentation"

Quote:

CYLINDER ROUGHNESS
Substantial controversy exists on the correct cylinder roughness for proper seating of piston rings, whether chrome, moly, or plain cast iron. It has been our experience that the use of 220-280 grit stones and achieving proper cross hatch angle produces a finish compatible to all three types of the above rings.

Anybody know why the difference in recommended roughness ? 600 vs 280 is a significant difference. Is is just Hasting that recommends this. I just want to confirm the correct hone for my application. I beleive they are Hastings Powerflex rings. Thanks.

That does sorta make you wonder about their recommendation a little! I have always used Sealed Power rings for anything other than just High boosted or Nitrous applications that require something more exotic. And most of the regular moly equipped engines i've built get a much finer final hone than just a 600 grit. I have never considered Hastings to be a "top shelf" brand for any performance application, and none of the top engine builders in any of the motorsports fields that I personally know, use them either. They might be a decent middle of the pack product, and have their own methods for block preparation and recommendations. But if you follow their advice and have a sealing issue....then what, are they going to give you a whole new song and dance that they didn't tell you to begin with, or will they step up to the plate and address your problem(if you will even have one, just hypothetically speaking). Im sure others on here might have used their products in the past and might not have had any issues, that can expand on their experiences with the cylinder finish recommendations.

I use the 280 grit on my Hasings Flex Racing rings and have not had any problem so far. I don't even have a 400 or 600 grit for my hone, not saying they are not required sometimes but I haven't used them. Someone else may clarify that.

Quote:

Originally Posted by y2k600f4

I have read that Moly and Plasma-Moly top compression rings need a final hone that is fine; around 600 grit. However Hastings recommends 280 grit (talked to tech support). Also from their documentation"

Anybody know why the difference in recommended roughness ? 600 vs 280 is a significant difference. Is is just Hasting that recommends this. I just want to confirm the correct hone for my application. I beleive they are Hastings Powerflex rings. Thanks.

I have read that Moly and Plasma-Moly top compression rings need a final hone that is fine; around 600 grit. However Hastings recommends 280 grit (talked to tech support). Also from their documentation"

Anybody know why the difference in recommended roughness ? 600 vs 280 is a significant difference. Is is just Hasting that recommends this. I just want to confirm the correct hone for my application. I beleive they are Hastings Powerflex rings. Thanks.

Different ring finishes (chrome, moly, plain) prefer different wall finishes. Chrome will tolerate and needs a course finish to assist break in of the surfaces. A raw iron ring also like a rough finish but for a different reason which is more oil retention in the wall. The chrome ring doesn't need so much oil on the wall but needs to shape the wall to its contours.

Moly prefers a smoother wall to prevent early wearing of the coating. Moly lke chrome doesn't need as much upper cylinder lube but gets there by supplying its own slipperiness where chrome is simply resistant to wear in a low lubrication environment.

However super smooth walls as you get with a 600 finish tends to be too smooth, the current thinking is what's called plateau honing which combines both rough and smooth features. This process first puts a 250-300 finish on the wall then comes back with a 400-600 stone to break the rough edges of the first coarser cut. This provides both more oil retention in the coarse hatch for the lower rings and the thrust skirt with a smoother surface from the finer hatch that the moly ring likes.

This process first puts a 250-300 finish on the wall then comes back with a 400-600 stone to break the rough edges of the first coarser cut. This provides both more oil retention in the coarse hatch for the lower rings and the thrust skirt with a smoother surface from the finer hatch that the moly ring likes.

Makes total sense and I have read about this method, seems the norm. Why don't these manufacture's recommendations line up with industry standards? Makes me wonder that possibly the manufacture's don't know their own products and are not concerned about early "sanding" of the moly finish due to a courser hone.

Makes total sense and I have read about this method, seems the norm. Why don't these manufacture's recommendations line up with industry standards? Makes me wonder that possibly the manufacture's don't know their own products and are not concerned about early "sanding" of the moly finish due to a courser hone.

Probably an old recommendation that should be updated but likely won't be.

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